Is plasticity in partitioning of photosynthetic resources between and within leaves important for whole-plant carbon gain in canopies?
Is plasticity in partitioning of photosynthetic resources between and within leaves important for whole-plant carbon gain in canopies?
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DOI：
10.1111/j.0269-8463.2004.00895.x
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发表时间：
2004-12
影响因子：
5.2
通讯作者：
T. Pons;N. Anten
中科院分区：
文献类型：
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作者：
T. Pons;N. Anten
1.通过实验和模拟的方法，研究了光合作用资源叶间和叶内分配对全株碳可塑性的意义。在温室内以两种不同的林分密度和两种养分利用率水平种植金钱草。计算了四个处理的全株日碳增量。研究了这两种可塑性在光合作用资源分配中的重要性，通过改变叶片氮和单位叶绿素的光合作用能力在两种林分密度下的植物之间的分配模式，并重新计算作为适合度的全株C增益。2.林分密度较大的林分，上部叶单位叶面积的光合能力较高，下部叶的单位叶面积的光合能力较低。疏林分在株高上的分布较为均匀。这种叶间资源分配的可塑性对整个植株的碳吸收并不是很重要，前提是植物具有密冠型分配。然而，有人争辩说，模型计算的结果只适用于低养分利用率，而不适用于高养分利用率。3.单位叶绿素的光合作用能力也表现出对林分密度的可塑性，这一参数代表了光合作用资源在能力和采光之间的分配。疏林和密林上部叶的单位叶绿素含量较高，而密林的遮荫下部叶单位叶绿素含量较低。在密度不同的林分中，这一性状的可塑性对植物的碳吸收也不是很重要。这里的条件是植物有露地植物的分布模式。然而，在从属植物的情况下，所有的叶子都在较高的邻居的阴影下，单位叶绿素的光合作用能力对整个植物的C增益来说要重要得多。
1. The significance for whole-plant carbon gain of plasticity in between-leaf and within-leaf partitioning of photosynthetic resources was investigated using an experimental and modelling approach. Lysimachia vulgaris L. was grown at two contrasting stand densities and two levels of nutrient availability in a glasshouse. Whole-plant daily C gain was calculated for the four treatments. The importance of the two forms of plasticity in photosynthetic resource partitioning was investigated by switching distribution patterns of leaf nitrogen and photosynthetic capacity per unit chlorophyll between plants in the two stand densities and recalculating whole-plant C gain, which was used as a measure of fitness. 2. The plants had a high photosynthetic capacity per unit leaf area in top leaves in the dense stands, and a low capacity in bottom leaves. The distribution over plant height was more homogeneous in the open stands. This plasticity in between-leaf resource partitioning was not very important for whole-plant C gain, provided the plants had a dense-canopy type of partitioning. It is argued, however, that this result of the model calculations is valid only for low, but not high, nutrient availability. 3. Photosynthetic capacity per unit chlorophyll, a parameter representative of within-leaf partitioning of photosynthetic resources between capacity and light harvesting, also showed plasticity in response to stand density. High values were found in open stands and in the top leaves in dense stands, whereas a low capacity per unit chlorophyll was found in shaded bottom leaves in dense stands. Plasticity in this trait was also not very important for C gain of plants in stands of contrasting densities. Here the condition was that plants have a distribution pattern found for open-stand plants. However, in the case of subordinate plants that have all their leaves in the shade cast by their taller neighbours, adjustment of photosynthetic capacity per unit chlorophyll to the level of irradiance is much more important for whole-plant C gain.